Conventionally, there have been attempts to effectively utilize energy from vibration of structures such as a road, a bridge, and architecture, vibration of vehicles such as an automobile and a railway vehicle, and vibration from human exercise. An example of a method for effectively utilizing energy from vibration includes a method of converting vibration energy to electrical energy. Examples of thereof include a method utilizing a piezoelectric element and a method utilizing electrostatic induction.
The method utilizing a piezoelectric element mainly uses a ceramic-based piezoelectric element, and utilizes a phenomenon in which charges are induced on a surface of the piezoelectric element when vibration applies distortion to the piezoelectric element.
The method utilizing electrostatic induction generally uses an electret dielectric which has an electrical charge semipermanently (e.g., see PTLs 1 to 3). The electret dielectric used in the method is a material which allows a dielectric to be charged to thereby generate an electrostatic field semipermanently. The electrical charge is electrostatically induced on an electrode by changing a relative position between the electret dielectric and the electrode arranged apart from the electret dielectric through, for example, vibration. Thus, electric power is generated.